Seminar
Quantum cooperativity and rate analysis for atomic ensemble based quantum repeaters
Speaker: Siddardha Chelluri ((Johannes Gutenberg University, Mainz))
The bizarre idea of quantum entanglement led to a paradigm change in establishing secure communication via Quantum Key Distribution (QKD) schemes. However, as the loss in the channel/optical fibers is exponentially scaled with the distance, "quantum repeaters" are required for long distance secure communication. In this talk, an atomic ensemble based (quantum) repeater protocol (DLCZ [1]) is discussed. On the other hand, extensive studies on atomic and condensed matter systems with the interactions of light revealed interesting cooperative phenomena like Superradiance. Therefore possible enhancements for repeaters using "quantum cooperative" phenomena like superradiance is discussed. Furthermore, to theoretically quantify the efficiencies of various repeater protocols, a rate analysis procedure based on Markov chain model is introduced [2]. The aim of this talk is to bridge abstract theoretical analysis and experimental implementations of quantum repeater protocols.
[1] Duan, LM., Lukin, M., Cirac, J. et al. Long-distance quantum communication with atomic ensembles and linear optics. Nature 414, 413–418 (2001).
[2] Waiting time in quantum repeaters with probabilistic entanglement swapping. E. Shchukin, F. Schmidt, and P. van Loock. Phys. Rev. A 100, 032322 (2019).